Device for detecting the presence of yarn fed to needles on knitting and hosiery machines

ABSTRACT

The invention concerns knitting and hosiery machines and in particular a system for detecting the presence of yarn being fed to the needles on the cylinder of such machines. Each yarn is fed to the needles through a yarn guide moving between an out of work to a work position and is associated with a sensor capable of detecting movement/presence of the yarn and to stop the machine when the yarn guide moves from the out of work to the work position and there is no movement/presence of the yarn.

FIELD OF INVENTION

[0001] The present invention concerns the knitting machines in general,and in particular a control device for the presence of yarns beingsupplied to the needles of circular knitting and hosiery machines and tostop the machine if there is a lack in the feeding of yarn.

STATE OF THE TECHNIQUE

[0002] Circular knitting and hosiery machines usually have a rotatingcylinder and use needles located on said cylinder and each provided witha tongue movable between open and close position.

[0003] In normal work, the stitch is made by supplying the needles withone yarn. If this yarn, for whatever reason, breaks or fails to besupplied, the tongue of the needles remain open, protrude due tocentrifugal force and a mechanical sensor reveals their presence,causing the machine to stop.

[0004] However, in the field of the knitting machines and more preciselyfor the production of stockings, work known as “in vanisè” is oftencarried out where the stitch is formed using two or more yarns which caneither be one on top of the other or not so as to be one face and oneback, according to requirements.

[0005] For a “in venisè” working, one needle is fed by two or more yarnssupplied from respective different yarn guides, each movable betweenidle and working positions. Consequently , in the case of breakage orlack of feeding even of only one of the two yarns, the needle tonguecontinues to work normally with the yarn which is available, thereforethe machine is not stopped and continues to proceed to produce faultymanufactured articles which have to be rejected.

[0006] Stopping a knitting or hosiery machine because of a breakage orlack of feeding of a yarn, when the needles are fed with two or moreyarns at the same time, therefore causes a problem.

[0007] To avoid this problem, a system which memorises the flow of theyarns being supplied during the production of a first manufacturedarticle to achieve self-learning on the part of the textile machine, wasproposed. The system includes sensors associated with the various yarnsand a computer which manages these sensors and which stop the machineif, during production of each successive manufactured article, avariation in flow is detected even in one yarn, either because it isbroken or there is a lack of feeding. This system involves however theuse of sensors, which must send signals to a computer corresponding tothe flow of the various yarns during the production of the firstmanufactured article, and software and programming to compare thesuccessive flows of the yarns with those which have been memorised andto stop the machine should a variation be found. Furthermore, each timethe article to be made is changed, all the manufacturing process for thenew article has to be memorised.

OBJECT AND SUMMARY OF THE INVENTION

[0008] This invention is aimed at resolving the above mentioned problemin a new and original way and above all in a way which is much simplerand economic.

[0009] One of the objects of this invention is in fact, to provide asystem to control the presence of the yarns being fed in combination tothe needles of a circular hosiery and knitting machine, which neitherrequires self-learning on the part of the machine nor consequentlysophisticated electronics, and which is completely independent of thecharacteristics of the manufactured article to be made and/or from thefact that this may be modified or replaced by a new one.

[0010] This object is achieved, according to the invention, byassociating each yarn being fed to the needles of a textile machinethrough a yarn guide, with a sensor capable of detecting flow/presenceof the yarn itself, and stopping the machine when the yarn guide ismoved from an idle position to a feeding position and the sensor doesnot detect flow of the relative yarn.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The invention will be described in detail in the continuation ofthis description made in reference to the enclosed drawing in which, theonly figure shows a the schematic view of a cylinder with needles and ayarn guide in the work and out of work idle positions.

[0012] The type of circular hosiery or knitting machine taken intoconsideration here, usually includes a cylinder 11 housing needles 12controlled and moving in the known way, to collect one or more yarns 13to be knitted according to a knitting programme. Each yarn 13 comes froma respective reel 14 and is guided and supplies the needles 12 through ayarn guide 15 which moves between an out of work, idle position A, at acertain distance from the needles, and a work position B close to theneedles, as shown in the drawing.

[0013] When the yarn guide 15 is in the out of work, idle position A,the yarn 13 is not fed to the needles 12, remaining in this way excludedfrom the knitting process; on the other hand the yarn guide 15 is placedin work position B when the relative yarn is required to feed theneedles and knitted alone or together with at least one other yarn, asin the case of “in vanisè” manufacture, for example.

[0014] According to this invention, yarn 13, being fed to each yarnguide 15, is associated with a sensor 16 able to detect the flow, andconsequently also the presence of the yarn to the yarn guide. The sensor16, which can be of a known type, is connected to the electric circuitof the motor which drives and controls the cylinder 11 rotation and tothe means which cause the in and out of work movements of the yarn guide15.

[0015] In particular, the sensor is devised and acts in combination withthe yarn guide 15 to keep the electric circuit on the motor closed sothat the latter and therefore the machine operate when the yarn guide isin the work position and the yarn, on flowing, regularly passes throughthe yarn guide and consequently supplies the needles for a correctformation of the stitches. On the other hand, if the sensor does notdetect flow/presence of the yarn when the respective yarn guide passesfrom the out of work, idle position to the work position, it causes theelectric circuit on the motor to open and stop the machine so as toprevent the manufacture of faulty articles and rejects due to the lackof supply of the yarn.

[0016] In other words, in compliance with the system of the invention, aknitting or hosiery textile machine is stopped when any yarn guide isplaced in the work position to feed the needles on the cylinder and therelated sensor does not detect movement of the yarn to the yarn guideitself.

1. A system for controlling the presence of the yarns being fed to theneedles on the cylinder of circular knitting and hosiery machines withthe object of stopping the machine when a lack of yarn occurs, and whereeach yarn being supplied through a yarn guide moving from an out ofwork, idle position to a work position, characterised by the feature ofassociating each yarn feeding the needles through a related yarn guide,with a sensor capable of detecting the flow/presence of the yarn itself,and to cause the stop of the machine when the yarn guide is moved fromthe out of work position to the work position and said sensor releases asignal which is indicative of absence of flow of the related yarn tosaid yarn guide.
 2. The system according to claim 1, wherein the sensorassociated with each yarn is placed in connection with the electriccircuit of a motor which drives and controls the rotation of thecylinder with needles of the machine and with means controlling the inand out of work movements of the yarn guide corresponding to said yarn,so that the movement of the yarn guide to the work position concurrentwith a failure to detect movement of the yarn on the part of said sensorcauses the electric circuit to open, stopping the machine.